Nitrogen-doped carbon species: a promising nonmetallic promoter for the Co/SiO2 Fischer–Tropsch synthesis catalyst

Abstract

A dicyandiamide (DCDA)-additive impregnation method was used to prepare SiO₂ supported Co catalyst (i.e. Co/SiO₂-CN). The addition of DCDA molecules could produce nitrogen-doped carbon species with predominant pyrrolic nitrogen atoms on the SiO₂ support. The nitrogen-doped carbon species formed not only improved the reduction of Co₃O₄ particles, but also facilitated the electron transfer from the pyrrolic nitrogen atoms to neighboring metallic Co⁰ particles during reduction on the Co/SiO₂-CN catalyst, in contrast to the conventional impregnation derived Co/SiO₂-IWI sample. Such an effect ameliorated the electron-deficient state of metallic Co⁰ particles that existed on the Co/SiO₂-IWI catalyst and was favorable to CO dissociation. As a result, the DCDA-additive method derived Co/SiO₂ shows a higher turnover frequency value than the conventional Co/SiO₂-IWI catalyst in the Fischer–Tropsch synthesis reaction.